Last Updated on December 09, 2008

10 years ago Mount Pinatubo in the Philippines erupted spewing ash and lava across the countryside northwest of Manila. A lake in the crater was formed later which has slowly filled with rainwater creating a potential disaster. If the side of the volcano’s crater were breached, an avalanche of 60 million cubic meters of water, combined with mud, ash and volcanic debris -- called lahar could inundate the surrounding villages and farmland.

In an effort to stop an impending disaster, some 40,000 residents are being evacuated as vulcanologists bleed 24 million cubic meters of water through the lowest point on its rim, a crack known as the Maraunot notch. It remains to be seen whether the gradual draining operation will ease water pressure on the crater wall or lead to its collapse sending a wall of water down the volcano. 

Crater lake begins to drain

Scientists drill volcano

Fire and water menace

Latest Pinatubo photos

Draining of crater lake

Map of the crater

Philippine crater lake begins to drain

September 6, 2001 Posted: 8:27 AM EDT (1227 GMT)

Thousands have started to move to evacuation centers and higher ground

BOTOLAN, Philippines (CNN) -- In an operation considered one of the largest of its kind, the draining of a volcanic lake in the Philippines has begun.

After a slow start, water was by early afternoon streaming through a canal dug on the west bank of the crater lake.

The 75-meter-long canal has been constructed to reduce the threat of a deluge on a town of 40,000 residents below the Mount Pinatubo volcano in Zambales province, northwest of Manila.

Villagers had been evacuated for fear the volcano wall could collapse during the operation, sending a torrent of water thundering down the mountainside.

But the initial outcome has proved far less dramatic, with little more than harmless streams of muddy brown water barely wetting the ankles of workers in the channel.

Philippine Institute of Volcanology and Seismology (Phivolcs) director Raymundo Punongbayan said the emergency spillway dug by government workers and local Aeta tribesmen did not slope as steeply as planned.

"The gradient apparently is not correct for the drain canal," he said. "The gradient is so low that the flow is almost static."

Flow increased

A squad of soldiers and policemen were immediately called in to help deepen the canal and by late afternoon had managed to increase the outpouring to a slow but steady stream.

Scientists decided to drain the massive lake after its waters rose to critical levels following weeks of monsoon rains, threatening to cause a dangerous overflow.

Thousands of villagers fled to emergency shelters in adjacent towns Wednesday, but hundreds of families living in the center Botolan, a coastal town facing the South China Sea, refused to go, saying looters might break into their homes.

The draining aimed to release about a tenth of the estimated 250 million cubic metres of water in the crater lake and direct it through river channels and out into the South China Sea.

This would minimize the risk of an overflow in which torrents of water could sweep up tonnes of volcanic ash and boulders deposited on the slopes of the 1,445-meter (4,667-foot) high volcano and hurl them at Botolan, scientists said.

Scientists drill volcano to stop deadly delugeSeptember 5, 2001 Posted: 11:30 PM EDT (0330 GMT)

BOTOLAN, Philippines (CNN) -- The draining of a volcanic lake in the Philippines to prevent a deadly deluge on a town of 40,000 residents below has begun.

Workers with high pressure water hoses have started blasting a notch into Mount Pinatubo's summit to breach the volcano's crater and drain the lake that could unleash mass floods on the area.

Scientists fear that the Philippines' rainy season from June until late October could shatter the volcano's upper walls unleashing flash floods, threatening human lives in the Botolan municipality.

But breaching the crater is a dangerous operation with a 20 percent chance of also releasing floodwaters that could sweep through 18 villages as far as 40 kilometers (25 miles) away, scientists said.

Many residents have already evacuated and dozens of trucks and buses stood by to take away others if flood waters approach.

Hundreds of villagers, however, carried on with their lives, despite flood fears and an evacuation order.

Ash deposits

The volcanic lake was formed during the 1991 eruption of Mount Pinatubo, and rain water in past years has already filled the lake to only a few meters from the crater's rim.

Ash deposits from the 1991 eruption pose a further threat since these could mix with overflowing lake water and form an erosive volcanic mud known as lahar.

The Philippine government has spent more than $19.6 million to build a so-called mega-dike to prevent further lahar damage on towns along river channels.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said the operation would take several days, presuming the crater wall did not collapse during the operation -- an outcome they still said was a 20 percent chance.

The crater-lake of Pinatubo volcano

"We are prepared for a worst-case scenario but we don't foresee any complications," General Melchor Rosales, executive officer of the National Disaster Coordinating Council, told CNN.

Refusing to leave

Scientists have dug an emergency canal through a wall of the crater to direct the waters down river channels and into the South China Sea.

About 2,000 people died when a crater-lake breached on the Casita volcano in Nicaragua in 1998 buried two villages in a matter of minutes.

Some 8,000 residents were moved Wednesday in dump trucks and buses and any other available means of transport to local schools serving as evacuation centers.

Food, clothing and medicine have been provided since two weeks ago, with the help of the social welfare department, Rosales said.

But disaster officials have been encountering pockets of resistance due to the reported lack of food and sanitation facilities at the temporary shelters.

Rosales said disaster officials "would have no choice" but to forcibly move those who resist evacuation, adding it was up to local officials to enforce a deadline.

"The point is to put everybody out of harm's way and it was a consensus that the evacuation was the best solution for everybody," Rosales said.

"They could go back home safely in a few days," he added.

Pinatubo last erupted in 1991 and showered cities as far as Manila 130 km (80 miles) away with sulphuric ash. More than 800 people died in that eruption, mostly from diseases in congested evacuation camps.

Volcano menaces with fire and waterAugust 9, 2001 Posted: 5:18 AM EDT (0918 GMT)

MANILA, Philippines -- Ten years after raining fire in a huge eruption, the crater of Mount Pinatubo is filling with water that threatens to unleash mass floods and inundate villages.

Philippine officials say the trapped rainwater was rising to dangerous levels and they would have to dig a canal on the slopes to avert a disaster.

Local residents, using picks, shovels and jack hammers, will start the digging work in two weeks to allow the waters to flow down to a river and safely away from thousands of villagers living near the volcano, police commander Colonel Reynaldo Berroya told Reuters.

"This is the first time we are intervening with nature and hopefully the assessments are correct," Berroya said on local radio.

Up to 20 million cubic meters of water is expected to be released in the breaching operation, Zambales provincial governor Vicente Magsaysay told Manila's ANC television.

More than 800 people were killed when Pinatubo, 110 km (70 miles) northwest of Manila, erupted in 1991.

Last month, geologists commissioned by the British emergency agency Oxfam warned Pinatubo's crater wall was in danger of collapsing and that an avalanche of water and debris could engulf the town of Botolan and its 46,000 inhabitants.

The geologists said the avalanche could result in a catastrophe similar to the one caused by the crater-lake breached on the Casita volcano in Nicaragua in 1998 that buried two villages and killed about 2,000 people.

Berroya said the gap between the surface of the crater-lake water and the brim of Pinatubo volcano had narrowed sharply to five meters (16 feet) from 6.5 meters (21 feet) in recent weeks.

"The waters are rising fast at a rate of more or less one meter a month and could rise faster now that the rains have come," he said.

Mount Pinatubo is one of the Philippines' two most closely watched volcanoes.

The other monitored volcano, Mt. Mayon, 330 km (200 miles) southeast of Manila, has been erupting for nearly two weeks, spewing lava and molten rocks, but there have been no casualties.

The Associated Press & Reuters contributed to this report.

In this aerial photo, workers rush to dig a 5-meter deep notch or canal on the lowest part of the crater of the Mount Pinatubo volcano to drain its crater lake. A "gentle" flow of water spilled into the nearby Bucao River.

An aerial view of Mount Pinatubo volcano, 80 kilometers (50 miles) northwest of Manila, shows its brimming crater lake. Some 40,000 residents have begun to move to higher and safer ground in order to avoid a potential deluge as the lake is partially drained.

Water began trickling out of the mountain as Aeta tribesmen construct a canal to drain the crater lake of Mount Pinatubo volcano. Volcanologists and engineers have begun draining water from the lake for fear of run-off or flash floods from the swollen lake.

The narrow cannel being built is aimed at draining the rising crater lake and averting flash floods. Several towns have been evacuated to safer areas as authorities expect the water to rise from the river where the crater water will be released.

A group of herdsmen lead their buffalos to a safe place as they pass the Bucao river, near Botolan. More than 40,000 residents are being evacuated.

Local residents use different forms of transportation, a buffalo drawn cart and a motorized tricycle, as they move to safer ground.